Crystalline, anhydrous forms of oxymorphone hydrochloride

ABSTRACT

Crystalline, anhydrous hydrochloride salts of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one (oxymorphone) are disclosed and three polymorphic forms of these salts are reported. The invention further relates to a method for the production of such salts, a pharmaceutical composition comprising an effective amount of such a salt and such a salt as a medicament and for the treatment and/or prevention of pain.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/EP2012/059705, filed May 24, 2012, which claims priority benefitunder 35 U.S.C. §119 of the U.S. Provisional Patent Application No.61/490,705, filed May 27, 2011, the disclosures of which patentapplications are incorporated herein by reference.

The present invention relates to a crystalline, anhydrous hydrochloridesalt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one(oxymorphone). The invention further relates to a method for theproduction of such a salt, a pharmaceutical composition comprising aneffective amount of such a salt and such a salt as a medicament and forthe treatment and/or prevention of pain.

Oxymorphone, generally administered in the form of its hydrochloridesalt, is a potent semi-synthetic opiate analgesic, for the relief ofmoderate to severe pain, and has been approved for use in the UnitedStates since 1959. It can be administered as an injectable solution,suppository, tablet or extended release tablet. In general, it iscommercially supplied as a monohydrate.

One of the more recent patent publications dealing with oxymorphonehydrochloride is US 2008/146601 A1 which discloses an improved analgesicoxymorphone hydrochloride that contains less than 10 ppm of alpha, betaunsaturated ketones and pharmaceutical preparations comprising suchoxymorphone hydrochloride. The oxymorphone hydrochloride is produced byreducing a starting material oxymorphone hydrochloride using gaseoushydrogen and under specified acidity, solvent system and temperatureconditions. A specific polymorph of oxymorphone hydrochloride may beobtained by hydration.

The crystal structure of the hydrochloride hydrate ethanol solvate isreported in S. D. Darling et al., J. Pharm. Sci. 1982, 71, 763 and thecrystal structure of the free base hydrate in R. J. Sime et al., ActaCrystallographica Section B 1976, 32, 2937.

As a rule, the crystalline state of an active pharmaceutical substancehas the advantage of an increased stability and processability.

A disadvantage of crystalline hydrates however is the possibility ofsolvent molecules also entering the crystal lattice. Furthermore, themicrobiological contamination of hydrates may be accelerated whencompared to substances lacking water.

It would therefore be desirable to have access to oxymorphonehydrochloride forms lacking these drawbacks. The present invention hasthe object of addressing these needs and of providing such oxymorphonehydrochloride salts.

According to the present invention this object is achieved by acrystalline, anhydrous hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one according to formula(I):

The compounds according to the invention are present in a crystallinestate which is conveniently defined as the presence of one or preferablymore reflexes in an X-ray powder diffractogram. In this respect the term“X-ray crystalline” is also used.

Besides avoiding the above-mentioned drawbacks in the art the anhydrouscrystalline salts of the invention also have the advantage that no watercontent needs to be checked prior to employment in production and thatno anisotropic water distribution within one storage vessel can occur.

In an embodiment of the hydrochloride salt according to the inventionthe melting or sublimation temperature, defined as the peak temperaturein a differential scanning calorimetry measurement at a heating rate of10° C./minute, is ≧250° C. Preferably, this temperature in a range of≧280° C. to ≦290° C. and more preferred ≧285° C. to ≦286° C. Thenormalized integral of the melting enthalpy thus obtained is preferablyin a range of ≧30 J/g to ≦40 J/g and more preferably ≧32 J/g to ≦34 J/g.

It has also been discovered that the crystalline, anhydrous oxymorphonesalts of the present invention may be obtained in several polymorphicforms. Polymorphism, the occurrence of different crystal forms, is aproperty of some molecules and molecular complexes. A single moleculemay give rise to a variety of polymorphs having distinct crystalstructures and physical properties like melting point, x-ray diffractionpattern, infrared absorption fingerprint, and solid state NMR spectrum.One polymorph may give rise to thermal behavior different from that ofanother polymorph. Thermal behavior can be measured in the laboratory bysuch techniques as capillary melting point, thermogravimetric analysis(“TGA”), and differential scanning calorimetry (“DSC”), which have beenused to distinguish polymorphic forms.

The difference in the physical properties of different polymorphsresults from the orientation and intermolecular interactions of adjacentmolecules or complexes in the bulk solid. Accordingly, polymorphs aredistinct solids sharing the same molecular formula yet having distinctadvantageous physical properties compared to other polymorphs of thesame composition or complex.

The discovery of new polymorphic forms and solvates of apharmaceutically useful composition provides a new opportunity toimprove the performance characteristics of a pharmaceutical product. Itenlarges the repertoire of materials that a formulation scientist hasavailable for designing, for example, a pharmaceutical dosage form of adrug with a targeted release profile or other desired characteristic.Therefore, there is a need for additional polymorphs of oxymorphonehydrochloride.

Thus, in one particular embodiment of the hydrochloride salt accordingto the invention the X-ray powder diffractogram of the salt comprisesone or more of the following reflexes (±0.2 in 2θ): 12.7, 14.7, 16.2,17.1, 19.0. Preferably, the following reflexes (±0.2 in 2θ) are alsoincluded: 9.2, 13.8, 15.3, 19.9, 20.6, 21.7, 24.6, 31.9, 34.6.

In the context of the present invention this polymorph will be referredto as the “first polymorph”. It is most preferred that its X-ray powderdiffractogram comprises one or more of the following reflexes as statedin the following table 1 (±0.2 in 2θ and recorded using CuK_(α)radiation; the relative intensity I(rel) is 100 at most):

TABLE 1 X-ray powder diffractogram 2θ I(rel) 12.7 100 14.7 52 16.2 2817.1 25 19.0 24 9.2 55 13.8 18 15.3 38 19.9 53 20.6 30 21.7 22 24.6 4231.9 29 34.6 19

In another particular embodiment of the hydrochloride salt according tothe invention the X-ray powder diffractogram of the salt comprises oneor more of the following reflexes (±0.2 in 2θ): 6.0, 13.1, 13.6, 15.3,16.5, 22.4, 22.6, 24.1. Preferably, the following reflexes (±0.2 in 2θ)are also included: 12.1, 29.8.

It is possible that the reflexes at 22.4 and 22.6 may not be resolved asa double peak if the sample quality is low. The case of these two peaksmerging into one peak is also within the scope of the invention.

In the context of the present invention this polymorph will be referredto as the “second polymorph”. Its melting or sublimation enthalpy,determined in a differential scanning calorimetry measurement at aheating rate of 10° C./minute, may be in a range of ≧30 J/g to ≦35 J/g.

It is most preferred that its X-ray powder diffractogram comprises oneor more of the following reflexes (±0.2 in 2θ and recorded using CuK_(α)radiation; the relative intensity I(rel) is 100 at most):

TABLE 2 X-ray powder diffractogram 2θ I(rel) 6.0 36 13.1 100 13.6 5315.3 89 16.5 76 22.4 26 22.6 28 24.1 66 12.1 43 29.8 24

In another particular embodiment of the hydrochloride salt according tothe invention the X-ray powder diffractogram of the salt comprises oneor more of the following reflexes (±0.2 in 2θ): 8.3, 16.1, 18.6, 20.9,28.0, 29.9.

In the context of the present invention this polymorph will be referredto as the “third polymorph”. It is most preferred that its X-ray powderdiffractogram comprises one or more of the following reflexes (±0.2 in2θ and recorded using CuK_(α) radiation; the relative intensity I(rel)is 100 at most):

TABLE 3 X-ray powder diffractogram 2θ I(rel) 8.3 21 16.1 100 18.6 2520.9 26 28.0 28 29.9 21 6.7 21 9.3 74 10.4 29 11.5 58 11.8 69 20.0 36

The present invention is further directed to a method for the productionof a crystalline, anhydrous hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one of formula (I)according to one or more of claims 1-5, comprising the steps of:

-   -   providing a hydrate hydrochloride salt of        4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-on of formula        (I); and    -   heating to a temperature of ≧130° C. to ≦210° C.

It is preferred that the heating step takes place in such a way that thewater that has been liberated from the hydrate starting material isremoved and therefore cannot form hydrate systems again.

In one embodiment, the method according to the invention furthercomprises the step of grinding the hydrate hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one of formula (I) priorto heating. It has been found that introducing shear stress by grindinggreatly reduces the degree of crystallinity of the monohydrate salt.

In another embodiment of the method according to the invention theheating is conducted during a hot-melt extrusion process. This has theadvantage that the method can be integrated into the production oftamper-resistant formulations of oxymorphone hydrochloride.

A further aspect of the present invention is a pharmaceuticalcomposition comprising an effective amount of a crystalline, anhydroushydrochloride salt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-oneof formula (I) according to the invention.

The quantity of the crystalline, anhydrous oxymorphone hydrochlorideamounting to an effective amount of this substance depends substantiallyon the type of formulation and on the desired dosage during the periodof administration. The quantity of the respective compounds to beadministered to the patient may vary and is, for example, dependent onthe weight or age of the patient and also on the manner ofadministration, on the indication and on the degree of severity of theillness. Preferably 0.005 mg/kg to 5000 mg/kg, particularly preferably0.05 mg/kg to 500 mg/kg, quite particularly preferably 0.5 mg/kg to 100mg/kg, still more preferably 2 mg/kg to 20 mg/kg of body weight of thepatient of at least one such compound are administered.

Oral formulations may be solid formulations, for example tablets,capsules, pills and pastilles, but oral formulations may also be liquidformulations, for example solutions, suspensions, syrups or elixirs.Liquid and solid formulations also encompass the incorporation of thecrystalline, anhydrous oxymorphone hydrochloride into solid or liquidfoodstuffs. Furthermore, liquids also encompass solutions for parenteralapplications, such as, for example, solutions for infusion or injection.

The crystalline, anhydrous oxymorphone hydrochlorides can be useddirectly as powders (micronized particles), granulates, suspensions orsolutions, or they may be mixed with other pharmaceutically acceptableingredients and components and then pulverized, in order then to fillthe powders into capsules consisting of hard or soft gelatin, to presstablets, pills or pastilles, or in order to suspend or dissolve thepowders in a carrier for the purpose of preparing suspensions, syrups orelixirs. Tablets, pills or pastilles can be provided with a coatingafter pressing.

Pharmaceutically acceptable ingredients and components for the varioustypes of formulation are known as such. It may, for example, be aquestion of binding agents such as synthetic or natural polymers,medicinal carriers, lubricating agents, surfactants, sweetening agentsand flavoring agents, coating agents, preserving agents, dyestuffs,thickening agents, ancillary agents, antimicrobial agents and carriersfor the various types of formulation.

Examples of suitable binding agents include gum arabic, gum tragacanth,acacia gum and biodegradable polymers such as homopolyesters orcopolyesters of dicarboxylic acids, alkylene diols, polyalkylene glycolsand/or aliphatic hydroxycarboxylic acids; homopolyamides or copolyamidesof dicarboxylic acids, alkylenediamines and/or aliphatic aminocarboxylicacids; corresponding polyester-polyamide copolymers, polyanhydrides,polyorthoesters, polyphosphazenes and polycarbonates. The biodegradablepolymers may be linear, branched or crosslinked. Specific examples arepolyglycolic acid, polylactic acid and poly-d,l-lactic/glycolic acid.Other examples of polymers are water-soluble polymers such as, forexample, polyoxaalkylenes (polyoxyethylene, polyoxypropylene and mixedpolymers thereof), polyacrylamides and hydroxyl-alkylatedpolyacrylamides, polymaleic acid and esters or amides thereof,polyacrylic acid and esters or amides thereof, polyvinyl alcohol andesters or ethers thereof, polyvinyl imidazole, polyvinyl pyrrolidone andnatural polymers, such as chitosan, for example.

Examples of medicinal carriers include phosphates, such as dicalciumphosphate.

Examples of suitable lubricating agents include natural or syntheticoils, fats, waxes or fatty-acid salts such as magnesium stearate.

Surfactants (surface-active agents) may be anionic, cationic, amphotericor neutral. Examples of useful surfactants include lecithin,phospholipids, octyl sulfate, decyl sulfate, dodecyl sulfate, tetradecylsulfate, hexadecyl sulfate and octadecyl sulfate, sodium oleate orsodium caprate, 1-acylaminoethane-2-sulfonic acids such as1-octanoylaminoethane-2-sulfonic acid, 1-decanoylaminoethane-2-sulfonicacid, 1-dodecanoylaminoethane-2-sulfonic acid,1-tetradecanoylamino-ethane-2-sulfonic acid,1-hexadecanoylaminoethane-2-sulfonic acid and1-octadecanoylaminoethane-2-sulfonic acid, bile acids, salts andderivatives thereof, such as, for example, cholic acid, deoxycholicacid, taurocholic acid, taurodeoxycholic acid and sodium glycocholates,sodium caprate, sodium laurate, sodium oleate, sodium lauryl sulfate,sodium cetyl sulfate, sulfated castor oil, sodium dioctylsulfosuccinate, cocamidopropyl betaine and lauryl betaine, fattyalcohols, cholesterols, glycerin monostearate or distearate, glycerinmonooleate or dioleate, glycerin monopalmitate or dipalmitate andpolyoxyethylene stearate.

Examples of suitable sweetening agents include sucrose, fructose,lactose and aspartame.

Examples of useful flavoring agents include peppermint, oil ofwintergreen or fruit flavor such as cherry or orange flavor.

Examples of suitable coating agents include gelatins, waxes, shellac,sugars and biodegradable polymers.

Examples of preservation agents include methylparaben or propylparaben,sorbic acid, chlorobutanol and phenol.

Examples of ancillary agents include aromatic principles.

Examples of suitable thickening agents include synthetic polymers, fattyacids, fatty-acid salts, fatty-acid esters and fatty alcohols.

Examples of suitable liquid carriers include water, alcohols (ethanol,glycerol, propylene glycol, liquid polyethylene glycols), polytriazinesand oils. Examples of solid carriers are talc, aluminas,microcrystalline cellulose, silicon dioxide, aluminium oxide and similarsolid substances.

The composition according to the invention may also contain isotonicagents such as, for example, sugars, physiological buffers and sodiumchloride.

The composition according to the invention may also be formulated as aneffervescent tablet or effervescent powder which decomposes in anaqueous environment, thereby formulating solutions or suspensions fordrinking.

A syrup or a elixir may contain the crystalline, anhydrous oxymorphonehydrochloride, a sugar such as sucrose or fructose by way of sweeteningagent, a preserving agent (such as methylparaben), a dyestuff and aflavoring agent (such as flavoring substances).

The composition according to the invention may also be a formulationwith delayed and/or controlled release of the active substance uponcontact with body fluids of the gastrointestinal tract, in order toachieve a substantially constant and effective level of the activesubstance in the blood plasma. For this purpose the crystalline,anhydrous oxymorphone hydrochloride can be embedded in a polymer matrixof a biodegradable polymer, of a water-soluble polymer or of both typesof polymers, optionally together with a suitable surfactant. In thiscontext, ‘embedding’ may signify the incorporation of microparticlesinto the polymer matrix. Formulations with delayed and controlledrelease of active substance can also be obtained by encapsulation ofdispersed microparticles or emulsified microdroplets with the aid ofknown techniques for coating dispersions and emulsions.

The crystalline, anhydrous oxymorphone hydrochloride can also be usedtogether with at least one further pharmaceutical active substance forcombination therapies. To this end, at least one further activesubstance may be additionally dispersed or dissolved in the compositionaccording to the invention.

Yet another aspect of the present invention is a crystalline, anhydroushydrochloride salt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-oneof formula (I) according to the invention as a medicament. With furtherreference to the detailed description above, the medicament to theinvention may exist as a liquid, semisolid or solid medicinal form, forexample in the form of injection solutions, drops, juices, syrups,sprays, suspensions, tablets, patches, capsules, plasters,suppositories, ointments, creams, lotions, gels, emulsions, aerosols, orin multiparticulate form, for example in the form of pellets orgranulates, optionally pressed into tablets, filled in capsules orsuspended in a liquid, and may also be administered as such.

In a preferred manner, the medicament according to the invention issuitable for the treatment and/or prevention and/or inhibition of pain,preferentially of acute pain, chronic pain, neuropathic pain or visceralpain.

Finally, the present invention is also directed to a crystalline,anhydrous hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one of formula (I)according to the invention for the treatment and/or prevention of pain.

Examples for such pain to be treated and/or prevented are selected fromthe group consisting of acute pain, chronic pain, neuropathic pain andvisceral pain; of migraine; depressions; neurodegenerative diseases,preferentially selected from the group consisting of Parkinson'sdisease, Alzheimer's disease, Huntington's disease and multiplesclerosis; cognitive illnesses, preferentially cognitive deficiencyconditions, particularly preferably attention-deficit syndrome (ADS),panic attacks; epilepsy; coughing; urinary incontinence; diarrhea;pruritus; schizophrenia; cerebral ischemias; muscular spasms; cramps;food-intake disorders, preferentially selected from the group consistingof bulimia, cachexia, anorexia and obesity; abuse of alcohol and/ordrugs (in particular, nicotine and/or cocaine) and/or medicaments;dependence on alcohol and/or drugs (in particular, nicotine and/orcocaine) and/or medicaments, preferentially for the prophylaxis and/orreduction of withdrawal symptoms in the case of dependence on alcoholand/or drugs (in particular, nicotine and/or cocaine) and/ormedicaments; development of tolerance phenomena in relation tomedicaments, particularly in relation to opioids; gastro-oesophagealreflux syndrome; for diuresis; for antinatriuresis; for influencing thecardiovascular system; for anxiolysis; for heightening wakefulness; forheightening libido, for modulating motor activity and for localanaesthesia.

In a particularly preferred manner, the crystalline, anhydrousoxymorphone hydrochloride salt according to the invention is suitablefor the treatment and/or inhibition of pain, preferentially of acutepain, chronic pain, neuropathic pain or visceral pain; depressions;epilepsy; Parkinson's disease; abuse of alcohol and/or drugs (inparticular, nicotine and/or cocaine) and/or medicaments; dependence onalcohol and/or drugs (in particular, nicotine and/or cocaine) and/ormedicaments; preferentially for the prophylaxis and/or reduction ofwithdrawal symptoms in the case of dependence on alcohol and/or drugs(in particular, nicotine and/or cocaine) and/or medicaments; of thedevelopment of tolerance phenomena in relation to medicaments, inparticular in relation to opioids, or for anxiolysis.

Lastly, the present invention also encompasses a method of treating painin a subject in need thereof, said method comprising administering tosaid subject an analgesically effective amount of a crystallineanhydrous oxymorphone hydrochloride according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described with reference to thefollowing figures and examples without wishing to be limited in any way.

FIG. 1 shows an XRPD diagram of the reference material oxymorphonehydrochloride monohydrate

FIG. 2 shows a DSC diagram of the reference material oxymorphonehydrochloride monohydrate

FIG. 3 shows a TGA diagram of the reference material oxymorphonehydrochloride monohydrate

FIG. 4 shows an XRPD diagram of a first polymorph of crystallineanhydrous oxymorphone hydrochloride

FIG. 5 shows an XRPD diagram of a second polymorph of crystallineanhydrous oxymorphone hydrochloride

FIG. 6 shows a DSC diagram of the second polymorph of crystallineanhydrous oxymorphone hydrochloride

FIG. 7 shows a TGA diagram of the second polymorph of crystallineanhydrous oxymorphone hydrochloride

FIG. 8 shows an XRPD diagram of a third polymorph of crystallineanhydrous oxymorphone hydrochloride

All powder diffraction patterns were determined with a STOE STADI PX-ray powder diffractometer, transmission geometry (Debye-Scherrer),CuK_(α1) radiation, germanium monochromator, linear PSD, omega 2θ scanmode with a rotating flat sample. Variable temperature XRPD measurementswere processed with the same diffractometer and geometry but using acapton foiled oven and a glass capillary. Detection of the diffractedpattern was undertaken with a STOE IPPSD. The data processing andanalysis software used was Win XPOW® POWDAT.

Grinding experiments were carried out with a standard agate mortar at20-25° C. and a relative humidity of 40-60%.

Humidity experiments were carried out at 20-24° C. by use of a saturatedsodium chloride solution in an exsiccator, providing a relative humidityof approximately 70-75%.

DSC data were collected with a Mettler Toledo DSC821e/500 apparatus, AIstandard pan (40 μl; with pinhole; N₂). Thermogravimetric data wasobtained via a Mettler Toledo TGA/STDA module 851e.

Microscopic investigations were carried out with an Olympus BX51microscope equipped with a Linkam TMS94 hot stage.

For the purpose of a better reference FIG. 1 shows an XRPD diagram ofcommercially supplied oxymorphone hydrochloride monohydrate. The DSCthermogram of this material is depicted in FIG. 2.

In this diagram two relevant thermal events can be observed. Starting atapproximately 40° C. a broad endotherm is attributed to the loss ofwater, adhered water and the crystal water. The peak temperature of thisendotherm was at 146° C.

The endotherm with an onset at 210° C. and a peak at 230° C. cannot berelated to melting but to sublimation. This was confirmed by hot stagemicroscopy. The indication for sublimation is the broad endotherm andthe comparatively low heat of only ca. 38 J/g. The sublimation isfollowed by degradation. Hot stage experiments with sublimation at over200° C. only led to a degraded product. The sublimated materials werere-sublimated on a cold glass object plate. The resulting black solidwas analyzed by GC-MS. The molar peak of oxymorphone was not found butrather only degradation products were detected.

The TGA data as represented in FIG. 3 show events that are comparable tothose observed in the DSC experiment. The weight loss from 40-110° C.(onset temperature determined to be ca. 86° C.) represents the loss ofwater, 6.7% in total. Starting at ca. 210° C. the weight loss isattributed to sublimation/degradation.

FIG. 4 shows an XRPD diagram of a first polymorph of crystallineanhydrous oxymorphone hydrochloride. This material was produced by thefollowing procedure: either crystalline oxymorphone hydrochloride orground, mainly amorphous oxymorphone hydrochloride was heated to atemperature of 200° C. in a drying oven. The first polymorph wasobtained as colorless, needle-type crystals growing on a solid formsecond polymorph (as described below). The crystals were separatedmanually and an X-ray powder diffraction pattern was determined. TheXRPD peak list is given in the following table 4.

TABLE 4 XRPD data D 2θ I (rel) 9.63 9.17 55 6.98 12.66 100 6.39 13.83 186.01 14.71 52 5.78 15.31 38 5.75 15.38 38 5.45 16.23 28 5.16 17.14 254.88 18.16 12 4.79 18.47 13 4.65 19.04 24 4.60 19.25 16 4.45 19.92 534.31 20.55 30 4.09 21.71 22 3.85 23.06 13 3.81 23.32 14 3.65 24.36 213.61 24.59 42 3.57 24.89 16 3.50 25.40 13 3.48 25.54 13 3.36 26.49 163.19 27.87 16 3.09 28.81 18 2.99 29.76 11 2.95 30.21 13 2.87 31.11 112.80 31.85 29 2.68 33.35 15 2.58 34.63 19 2.46 36.42 10 2.32 38.69 92.13 42.24 9

After further heating of a mixture of the thus obtained first and secondpolymorphs the first polymorph disappeared. Possible explanations aresublimation (under degradation) or the transition onto the secondpolymorph.

FIG. 5 shows an XRPD diagram of the second polymorph of crystallineanhydrous oxymorphone hydrochloride. This polymorph was obtained by aheat treatment of either the above-described polymorph mixture or ofoxymorphone hydrochloride monohydrate at 200° C. for a period of 3-4hours in a drying oven. This form is stable at room temperature and atelevated temperatures and does not tend to transform into otherpolymorphs. The XRPD peak list is given in the following table 5.

TABLE 5 XRPD data D 2θ I (rel) 14.72 5.99 36 7.32 12.06 43 6.72 13.14100 6.50 13.60 53 6.18 14.30 20 5.78 15.30 89 5.37 16.47 76 3.96 22.4126 3.92 22.64 28 3.68 24.09 66 3.46 25.71 26 3.39 26.24 23 3.35 26.50 273.17 28.06 25 2.99 29.84 24 2.93 30.45 14 2.85 31.34 16 2.80 31.92 17

FIG. 6 shows a DSC diagram of the second polymorph. A first smallendotherm is found with the following data: onset 39.43° C., peak 68.66°C. and a normalized integral of 0.78 J/g. A glass transition was foundwith an onset of 166.50° C. and a center point of 168.52° C. The strongendotherm has the following data: onset 266.91° C., peak 285.09° C. anda normalized integral of 33.16 J/g.

The TGA diagram in FIG. 7 displays no weight loss until a temperature ofabout 220° C. where according to the DSC measurements the sublimationprocess starts.

A third polymorph of crystalline anhydrous oxymorphone hydrochloride wasobtained in the circumstances of a variable temperature XRPD experiment,namely in the environment of the X-ray capillary used therein. The XRPDdiagram of this third polymorph is shown in FIG. 8 and the XRPD peaklist is given in the following table 6.

TABLE 6 XRPD data D 2θ I (rel) 13.21 6.68 21 10.70 8.25 21 9.52 9.27 748.47 10.43 29 7.68 11.50 58 7.47 11.82 69 7.21 12.26 3 6.61 13.37 7 5.5116.05 100 5.09 17.38 7 4.87 18.17 6 4.77 18.57 25 4.44 19.97 36 4.2320.94 26 4.15 21.39 8 4.09 21.69 4 3.84 23.11 7 3.74 23.74 8 3.67 24.179 3.53 25.18 10 3.48 25.52 19 3.30 26.94 7 3.18 27.98 28 3.05 29.18 82.98 29.88 21 2.75 32.44 8 2.67 33.44 4 2.55 35.15 6

The invention claimed is:
 1. A crystalline, anhydrous hydrochloride saltof 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one according toformula (I):

wherein the hydrochloride salt exhibits an X-ray powder diffractogramwherein peaks are observed at a grouping of peaks selected from thegroup consisting of A, B and C: A) at (±0.2 in 2θ): 12.7, 14.7, 16.2,17.1 and 19.0; B) at (±0.2 in 2θ): 6.0, 12.1, 13.1, 13.6, 15.3, 16.5,22.4, 22.6, 24.1, 25.7 and 29.8; and C) at (±0.2 in 2θ): 8.3, 16.1,18.6, 20.9, 28.0 and 29.9.
 2. The hydrochloride salt according to claim1, wherein the melting or sublimation temperature, defined as the peaktemperature in a differential scanning calorimetry measurement at aheating rate of 10° C./minute, is ≧250° C.
 3. The hydrochloride saltaccording to claim 1, wherein the X-ray powder diffractogram of the saltcomprises the following peaks (±0.2 in 2θ): 12.7, 14.7, 16.2, 17.1, and19.0.
 4. The hydrochloride salt according to claim 1, wherein the X-raypowder diffractogram of the salt comprises the following peaks (±0.2 in2θ): 6.0, 12.1, 13.1, 13.6, 15.3, 16.5, 22.4, 22.6, 24.1, 25.7, and29.8.
 5. The hydrochloride salt according to claim 1, wherein the X-raypowder diffractogram of the salt comprises the following peaks (±0.2 in2θ): 8.3, 16.1, 18.6, 20.9, 28.0, and 29.9.
 6. A method for thepreparation of a crystalline, anhydrous hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one of formula (I)according to claim 1, comprising the steps of: providing a hydratehydrochloride salt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-onof formula (I); and heating to a temperature of ≧130° C. to ≦210° C. 7.The method according to claim 6, further comprising the step of grindingthe hydrate hydrochloride salt of4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-one of formula (I) priorto heating.
 8. The method according to claim 6, wherein the heating isconducted during a hot-melt extrusion process.
 9. A pharmaceuticalcomposition comprising an effective amount of a crystalline, anhydroushydrochloride salt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-oneof formula (I) according to claim
 1. 10. A method of treating pain in apatient in need of such treatment, said method comprising administeringto said patient an effective amount therefor of a crystalline, anhydroushydrochloride salt of 4,5α-epoxy-3,14-dihydroxy-17-methylmorphinan-6-oneof formula (I) according to claim 1.